To put it briefly, the other woman is routinely cast as the villain in instances of marital break up, and I think this is neither fair nor reasonable.
It has been suggested to me that a woman, especially a self-proclaimed feminist, has a duty of care towards her married sisters, which should oblige her to keep her nose - or anything else - out of their marriages. As a male, it is tempting to be offered a way of avoiding some of the responsibility for one's own actions, but it really won't wash. Even if a man is a stereotypically spineless creep, driven by his own poorly understood sexual urges, nobody except him is compelling him to act in this way. He cannot hide behind Eve like Adam and say "She made me do it".
I am not a student of Feminism, but from my understanding of it, on a point of ideology, feminists believe that men exercise disproportionate patriarchal power. This surely doesn't sit well with a view of women which would ascribe to them the power to act as the guardians of other people's marriages.
No, I'm afraid, men or women, those of us who have been instrumental in breaking up our marriages must take responsibility for having done it. I cannot hide behind the skirts of the other woman.
The impulse to blame a third party is understandable and touching; the refuge of love for those who cannot easily hate us. We are shielded from the full force of our former partner's rage by the luckless third party who gets it, in my view, undeservedly, or certainly disproportionately.
Now nobody would advocate the deliberate undermining of another's marriage. To deliberately disrupt a relationship by stirring things up, or to put pressure on someone to go beyond their own inclinations, would constitute unacceptable interference. Simply to find oneself in a relationship with someone, leaving them to decide what the consequences of that might be, is not interference at all. Undue interference is engaged in by other men as well as other women, and it is an issue completely separate from some imagined female duty to safeguard the sanctity of marriage.